A scanning device has an optical housing and an optical scanning unit known as an actuator. The optical housing can be moved like a slide obliquely or perpendicularly to the respective recording track of a disc-type optical recording medium (optical disc) and is known as a pick-up. It can be moved in a manner driven by electric motor with high speed and high positioning accuracy, in association with a short access time to different locations on the recording medium. The actuator emits a laser beam onto the recording medium and receives the beam reflected from there. The scanning unit having a focusing lens is mounted in an adjustable manner with a disc-type carrier on the housing, which is moveable on guide rods, in order to be able to orient the focusing lens with regard to the optical path of the optical housing. This last is necessary because the scanning device has a series of optical components for directing and orienting the laser beam on the path to the respective recording medium and from the latter to a detector, which, just like the mechanical parts that hold and connect these, have specific manufacturing and assembly tolerances.
In order that the respective optical disc can be illuminated in a positionally accurate manner and its data can be communicated precisely to the detector, provision is made for aligning the focusing lens during assembly of the scanning device by changing the inclination of the scanning unit, as is described for example in EP 0649130 A, EP 0872832 A and US 2001/0050899 A. In this case, the inclination is changed by means of the carrier about a virtual axis, said carrier resting with at least one sliding area on at least one carrying area integrally formed on the optical housing. The areas are formed in particular in spherical or cylindrical fashion, and the carrier is tensioned onto the carrying area with an adjusting screw arranged eccentrically on the housing and with a spring means arranged eccentrically and can be adjusted by turning the adjusting screw.
Tension springs and leaf springs are used as the spring means. The scanning device according to US 2001/0050899 A is provided with a leaf spring which is bent in a U-shaped manner, is fixed with one of its two limbs with a fixing section on the housing and bears elastically on the carrier with its other limb, the two limbs being inclined relative to the fixing section and the limb that bears on the carrier exerting an elastic contact force on the carrier, which force is inclined in its direction in relation to the axis of the adjusting screw. As a result, the contact force exerted on the carrier has a component perpendicular to the carrier and a component parallel to the latter, so that it is possible to set the angle of inclination of the carrier uniformly and with high sensitivity. The fixing section of the leaf spring is preferably established by a fixing screw on the housing. On account of the very small dimensions of the scanning unit, the positioning and fixing of the spring means is made more difficult, especially as the scanning unit is not fully accessible from all sides. Consequently, it may be regarded as disadvantageous that the leaf spring described requires a separate fixing element and increased assembly costs are incurred. Moreover, the leaf spring requires a structural space determined by its extent over and alongside the carrier. It is an object of the invention to improve a scanning device of this type.